From patchwork Fri Aug 17 10:27:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Torsten Duwe X-Patchwork-Id: 10568601 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5C54C1390 for ; Fri, 17 Aug 2018 10:27:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4522D2B49E for ; Fri, 17 Aug 2018 10:27:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 351622B4AC; Fri, 17 Aug 2018 10:27:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 816C42B49E for ; Fri, 17 Aug 2018 10:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:From:Date: Message-Id:References:In-Reply-To:Subject:To:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=BlmK+Ujawz0G9N9EANjMJDfSPh/TPcgkL7JMCSacCek=; b=MVKDvpzbM3NsRH07I6RZJEMwGZ xQT9FCRybOxroMVBlto2/ih19xlQhYWVKzwEMT338P4prk30A+uFiPPi3i+V4qvyqaZ4pgQmjPH6M IVT6WMoFFouPYLmrq8dnmwhHWs624paHmJCEWgddYyV/RerGAo3b5UBHwNQFkxgT7P9/riV59Sq8e WR9Ahv7arMMKPATkBI++hKhtFb2YhtSncbFsLvZWIT/nSOI4xO+UIwUqMMeN2q3bjJkeFtf2NCH0p SJvSOStVObbdrzkFx+t4yL7YGmRAfrjKZJ7uqLueaeE3yBj/lcgziVX8hHGUdnu2QfDh14Vlc/kwV wxgnQCdg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fqby7-00019m-Db; Fri, 17 Aug 2018 10:26:59 +0000 Received: from verein.lst.de ([213.95.11.211] helo=newverein.lst.de) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fqbxf-0000cb-Py for linux-arm-kernel@lists.infradead.org; Fri, 17 Aug 2018 10:26:35 +0000 Received: by newverein.lst.de (Postfix, from userid 2005) id 022FB68EF4; Fri, 17 Aug 2018 12:27:24 +0200 (CEST) To: Will Deacon , Catalin Marinas , Julien Thierry , Steven Rostedt , Josh Poimboeuf , Ingo Molnar , Ard Biesheuvel , Arnd Bergmann , AKASHI Takahiro Subject: [PATCH v2 1/3] arm64: implement ftrace with regs In-Reply-To: <20180817102544.C628D68EF4@newverein.lst.de> References: <20180817102544.C628D68EF4@newverein.lst.de> Message-Id: <20180817102724.022FB68EF4@newverein.lst.de> Date: Fri, 17 Aug 2018 12:27:24 +0200 (CEST) From: duwe@lst.de (Torsten Duwe) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180817_032632_143213_FF4BBE6A X-CRM114-Status: GOOD ( 11.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Check for compiler support of -fpatchable-function-entry and use it to intercept functions immediately on entry, saving the LR in x9. Disable ftracing in efi/libstub, because this triggers cross-section linker errors now (-pg is disabled already for those files). Add an ftrace_caller which can handle LR in x9, as well as an ftrace_regs_caller that additionally writes out a set of pt_regs for inspection. Signed-off-by: Torsten Duwe --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -110,6 +110,7 @@ config ARM64 select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE + select HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_TRACER --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -78,6 +78,15 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y) KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds endif +ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + CC_FLAGS_FTRACE := -fpatchable-function-entry=2 + KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY + ifeq ($(call cc-option,-fpatchable-function-entry=2),) + $(error Cannot use CONFIG_DYNAMIC_FTRACE_WITH_REGS: \ + -fpatchable-function-entry not supported by compiler) + endif +endif + # Default value head-y := arch/arm64/kernel/head.o --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -16,6 +16,13 @@ #define MCOUNT_ADDR ((unsigned long)_mcount) #define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#define REC_IP_BRANCH_OFFSET 4 +#else +#define REC_IP_BRANCH_OFFSET 0 +#endif + #ifndef __ASSEMBLY__ #include --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -7,9 +7,9 @@ CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$( AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET) CFLAGS_armv8_deprecated.o := -I$(src) -CFLAGS_REMOVE_ftrace.o = -pg -CFLAGS_REMOVE_insn.o = -pg -CFLAGS_REMOVE_return_address.o = -pg +CFLAGS_REMOVE_ftrace.o = -pg $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_insn.o = -pg $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_return_address.o = -pg $(CC_FLAGS_FTRACE) # Object file lists. arm64-obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -11,7 +11,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__K -fPIC -fno-strict-aliasing -mno-red-zone \ -mno-mmx -mno-sse -fshort-wchar -cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie +cflags-$(CONFIG_ARM64) := $(filter-out -pg $(CC_FLAGS_FTRACE)\ + ,$(KBUILD_CFLAGS)) -fpie cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ -fno-builtin -fpic -mno-single-pic-base --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -13,6 +13,8 @@ #include #include #include +#include +#include /* * Gcc with -pg will put the following code in the beginning of each function: @@ -123,6 +125,7 @@ skip_ftrace_call: // } ENDPROC(_mcount) #else /* CONFIG_DYNAMIC_FTRACE */ +#ifndef CC_USING_PATCHABLE_FUNCTION_ENTRY /* * _mcount() is used to build the kernel with -pg option, but all the branch * instructions to _mcount() are replaced to NOP initially at kernel start up, @@ -162,6 +165,88 @@ ftrace_graph_call: // ftrace_graph_cal mcount_exit ENDPROC(ftrace_caller) +#else /* CC_USING_PATCHABLE_FUNCTION_ENTRY */ +ENTRY(_mcount) + mov x10, lr + mov lr, x9 + ret x10 +ENDPROC(_mcount) + +ENTRY(ftrace_regs_caller) + stp x29, x9, [sp, #-16]! + sub sp, sp, #S_FRAME_SIZE + + stp x10, x11, [sp, #80] + stp x12, x13, [sp, #96] + stp x14, x15, [sp, #112] + stp x16, x17, [sp, #128] + stp x18, x19, [sp, #144] + stp x20, x21, [sp, #160] + stp x22, x23, [sp, #176] + stp x24, x25, [sp, #192] + stp x26, x27, [sp, #208] + + b ftrace_common +ENDPROC(ftrace_regs_caller) + +ENTRY(ftrace_caller) + stp x29, x9, [sp, #-16]! + sub sp, sp, #S_FRAME_SIZE + +ftrace_common: + stp x28, x29, [sp, #224] + + /* save function arguments */ + stp x0, x1, [sp] + stp x2, x3, [sp, #16] + stp x4, x5, [sp, #32] + stp x6, x7, [sp, #48] + stp x8, x9, [sp, #64] + + /* The link Register at callee entry */ + str x9, [sp, #S_LR] + /* The program counter just after the ftrace call site */ + str lr, [sp, #S_PC] + /* The stack pointer as it was on ftrace_caller entry... */ + add x29, sp, #S_FRAME_SIZE+16 /* ...is also our new FP */ + str x29, [sp, #S_SP] + + adrp x0, function_trace_op + ldr x2, [x0, #:lo12:function_trace_op] + mov x1, x9 /* saved LR == parent IP */ + sub x0, lr, #8 /* function entry == IP */ + mov x3, sp /* pt_regs are @sp */ + + .global ftrace_call +ftrace_call: + + bl ftrace_stub + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + .global ftrace_graph_call +ftrace_graph_call: // ftrace_graph_caller(); + nop // If enabled, this will be replaced + // "b ftrace_graph_caller" +#endif + +ftrace_common_return: + ldp x0, x1, [sp] + ldp x2, x3, [sp, #16] + ldp x4, x5, [sp, #32] + ldp x6, x7, [sp, #48] + ldp x8, x9, [sp, #64] + + ldp x28, x29, [sp, #224] + + ldr x9, [sp, #S_PC] + ldr lr, [sp, #S_LR] + add sp, sp, #S_FRAME_SIZE+16 + + ret x9 + +ENDPROC(ftrace_caller) + +#endif /* CC_USING_PATCHABLE_FUNCTION_ENTRY */ #endif /* CONFIG_DYNAMIC_FTRACE */ ENTRY(ftrace_stub) @@ -197,12 +284,20 @@ ENDPROC(ftrace_stub) * and run return_to_handler() later on its exit. */ ENTRY(ftrace_graph_caller) +#ifndef CC_USING_PATCHABLE_FUNCTION_ENTRY mcount_get_lr_addr x0 // pointer to function's saved lr mcount_get_pc x1 // function's pc mcount_get_parent_fp x2 // parent's fp bl prepare_ftrace_return // prepare_ftrace_return(&lr, pc, fp) mcount_exit +#else + add x0, sp, #S_LR /* address of (LR pointing into caller) */ + ldr x1, [sp, #S_PC] + ldr x2, [sp, #S_X28 + 8] /* caller's frame pointer */ + bl prepare_ftrace_return + b ftrace_common_return +#endif ENDPROC(ftrace_graph_caller) /* --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -70,7 +70,8 @@ int ftrace_update_ftrace_func(ftrace_fun */ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { - unsigned long pc = rec->ip; + unsigned long pc = rec->ip+REC_IP_BRANCH_OFFSET; + int ret; u32 old, new; long offset = (long)pc - (long)addr; @@ -128,22 +129,54 @@ int ftrace_make_call(struct dyn_ftrace * } old = aarch64_insn_gen_nop(); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#define INSN_MOV_X9_X30 aarch64_insn_gen_add_sub_imm(AARCH64_INSN_REG_9, \ + AARCH64_INSN_REG_30, 0, \ + AARCH64_INSN_VARIANT_64BIT, AARCH64_INSN_ADSB_ADD) + new = INSN_MOV_X9_X30; + ret = ftrace_modify_code(pc-REC_IP_BRANCH_OFFSET, old, new, true); + if (ret) + return ret; + smp_wmb(); /* ensure LR saver is in place before ftrace call */ +#endif new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK); return ftrace_modify_code(pc, old, new, true); } +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long pc = rec->ip+REC_IP_BRANCH_OFFSET; + u32 old, new; + + old = aarch64_insn_gen_branch_imm(pc, old_addr, true); + new = aarch64_insn_gen_branch_imm(pc, addr, true); + + return ftrace_modify_code(pc, old, new, true); +} + + /* * Turn off the call to ftrace_caller() in instrumented function */ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { - unsigned long pc = rec->ip; + unsigned long pc = rec->ip+REC_IP_BRANCH_OFFSET; bool validate = true; + int ret; u32 old = 0, new; long offset = (long)pc - (long)addr; +#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY + /* -fpatchable-function-entry= does not generate a profiling call + * initially; the NOPs are already there. + */ + if (addr == MCOUNT_ADDR) + return 0; +#endif + if (offset < -SZ_128M || offset >= SZ_128M) { #ifdef CONFIG_ARM64_MODULE_PLTS u32 replaced; @@ -188,7 +221,15 @@ int ftrace_make_nop(struct module *mod, new = aarch64_insn_gen_nop(); - return ftrace_modify_code(pc, old, new, validate); + ret = ftrace_modify_code(pc, old, new, validate); + if (ret) + return ret; +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + smp_wmb(); /* ftrace call must not remain without LR saver. */ + old = INSN_MOV_X9_X30; + ret = ftrace_modify_code(pc-REC_IP_BRANCH_OFFSET, old, new, true); +#endif + return ret; } void arch_ftrace_update_code(int command) --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -115,6 +115,7 @@ #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__mcount_loc)) \ + KEEP(*(__patchable_function_entries)) \ __stop_mcount_loc = .; #else #define MCOUNT_REC() --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -61,8 +61,12 @@ extern void __chk_io_ptr(const volatile #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) #define notrace __attribute__((hotpatch(0,0))) #else +#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY +#define notrace __attribute__((patchable_function_entry(0))) +#else #define notrace __attribute__((no_instrument_function)) #endif +#endif /* Intel compiler defines __GNUC__. So we will overwrite implementations * coming from above header files here